Backing a trailer involves making the tire do things no car tire needs to see (like twisting); it needs to be able to sit for 11 months yet spin up to 65MPH without warm up (and not fail!); it supports your camper without shocks yet is resistant to cupping from bouncing down the highway; it needs to support loads far in excess of a similar size car tire...

The stock Westlake ST tires on my A122 are 185R-13" Load Range D. I don't think I'm going to find any 13" car tires with a 1710 lb load rating - which is about 10% cushion over max GVWR. And I don't know of any LT 13" tires.

Also, I have not found that size ST tire in any brand besides Westlake (which have done have just fine for the first 3,000 miles). Given the lack of problems, I don't see any point in up-sizing my wheels (including spare) to get supposedly better tires.

being ignorant of trailer tire ins and outs for the first 30 years of my towing life, I always used passenger tires on my boat trailer (about 2,000 total pounds) and regularly towed it thousands of miles each year without any problems, blowouts, tire cupping or anything noticeable happening. I had 3 tire pairs over this time period, all but the first pair were Goodyear passenger car tires, 14" size. Last year I got my 4th set. I replaced the rims and tires with ST tires, only because I needed new rims and the mounted tires I got had ST rated tires already installed.

now that I have a tandem axle HTT, I better realize the stresses and added weight (4,600#) that I have on my trailer and I figure that ST tires of the proper size and inflation are the best that I can do

If you have 13" wheels, you are pretty limited to ST tires - I don't think you will find many 13" truck or passenger tires with that kind of load range. If you have 14" wheels, the Kumho Radial 857, an "all position" tire, has good capacity ratings and is very well liked by the single axle crowd - Casitas, etc.

You need to consider highway safety codes as well. There are lots of places that will not allow a trailer on the road with P or LT rated tires. Lots of tire shops also will not install them on trailers for liability concerns

You need to consider highway safety codes as well. There are lots of places that will not allow a trailer on the road with P or LT rated tires. Lots of tire shops also will not install them on trailers for liability concerns

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Where are these (Places) that check your (P or LT rated Tires)? Are they in the USA? Youroo!!

I run LT tires on my flatbed trailer. I see nothing special about ST tires. You can get LT tires at a higher weight rating per size then ST tires. As far as stresses I don't see anymore twisting of a trailer tires then if you sat in your vehicle and turned your front tires full left to right while not moving. I have never heard of anyone checking what type of tires were on a trailer.